wpf ComboBox binding in list view - wpf

Question

I have the problem with binding ComboBox in ListView
In ComboBox I need to bind User object from ListDetails object. If I change ComboBox it work, if I open window, binding don't work.
ComboBoxItem is a full list of all existing user from db.
<GridViewColumn x:Name="colUser" Header="User.Name in ComboBox">
<GridViewColumn.CellTemplate>
<DataTemplate>
<ComboBox Width="300" SelectionChanged="ComboBox_SelectionChanged"
ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:MainWindow}}, Path=AlleUser}"
SelectedValue="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ListViewItem}}, Path=DataContext.User}"
SelectedValuePath="Key" DisplayMemberPath="Value"/>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
full code you can see in https://github.com/fialo4ka/ListBinding/tree/master
In example I change db loading to some test data

Answer 1

So... After trying all this answers I still can't see the name of user in loading form, so I found the solution directly put Name to the ComboBox.
but I still can't understand why all previous solution is not working for me :(
private void ComboBox_Loaded(object sender, RoutedEventArgs e)
{
((ComboBox)sender).Text = ((ListDetails)((ComboBox)sender).DataContext).User.Name;
}
<DataTemplate>
<ComboBox Width="300" SelectionChanged="ComboBox_SelectionChanged" Loaded="ComboBox_Loaded"
ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:MainWindow}}, Path=AlleUser}"
SelectedValue="{Binding User}"
SelectedValuePath="Key" DisplayMemberPath="Key.Value"/>

Answer 2

You should bind to the User property of the ListDetails object:
<ComboBox Width="300" ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:MainWindow}}, Path=AlleUser}"
SelectedValue="{Binding User}"
SelectedValuePath="Key" DisplayMemberPath="Key.Name"/>

Answer 3

First, you should never mix data binding and setting values directly in code-behind.It makes debugging and understanding the code much more difficult for everybody, including yourself. Choose one. I highly recommend data binding. I refactored the code to use data binding only.
The below code works for me. Values are displayed in the ComboBox.
If this is still not working as expected, you have to clarify exactly what you are doing, what you are expecting and what is actually happening.
Also you usually don't set the ItemsControl.SelctedValue property. This property holds the result of the ItemsControl.SelectedValuePath, once an item is selected. In your case, when the selected value should be the User.Name value, you would need to set the path to SelectedValuePath="Key.Name" as the Key references the User item of the KeyValuePair and then Name the User.Name property. You would bind the SelectedValue to a property in your MainWindow class, to access it there or to another control, e.g. TextBlock.Text.
When reading new data from the database, you first clear the collections and then add the new items. Since you are using an ObservableCollection the views will update automatically. Don't set the views directly.
MainWindow.xaml
<Window>
<Grid>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<ListView Name="lvBezirke"
ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type main:MainWindow}}, Path=ListDetails}"
Grid.ColumnSpan="2">
<ListView.View>
<GridView ColumnHeaderToolTip="zugeordnete User je Bezirk">
<GridViewColumn x:Name="colBezirk" Header="Some Data from model" DisplayMemberBinding="{Binding Bezirk}" />
<GridViewColumn x:Name="colUser" Header="User.Name in ComboBox">
<GridViewColumn.CellTemplate>
<DataTemplate>
<ComboBox Width="300" SelectionChanged="ComboBox_SelectionChanged"
ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type main:MainWindow}}, Path=AlleUser}"
SelectedValuePath="Key" DisplayMemberPath="Value" />
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
<GridViewColumn Header="User.Loginname" DisplayMemberBinding="{Binding User.Loginname}" />
<GridViewColumn Header="User.Name" DisplayMemberBinding="{Binding User.Name}" />
</GridView>
</ListView.View>
</ListView>
<Button Grid.Row="1" Content="click" Click="Button_Click" />
<Button Grid.Row="1" Grid.Column="1" Content="clear" Click="Button_Click_1" />
<ListView Name="lvBezirkeClick"
ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type main:MainWindow}}, Path=ListDetailsClick}"
Grid.Row="2" Grid.ColumnSpan="2" >
<ListView.View>
<GridView ColumnHeaderToolTip="zugeordnete User je Bezirk">
<GridViewColumn Header="Some Data from model" DisplayMemberBinding="{Binding Bezirk}" />
<GridViewColumn Header="User.Loginname onClick" DisplayMemberBinding="{Binding User.Loginname}" />
<GridViewColumn Header="User.Name onClick" DisplayMemberBinding="{Binding User.Name}" />
</GridView>
</ListView.View>
</ListView>
</Grid>
</Window>
MainWindow.xaml.cs
partial class MainWindow
{
public ObservableCollection<ListDetails> ListDetails { get; set; }
public ObservableCollection<ListDetails> ListDetailsClick { get; set; }
public ObservableCollection<KeyValuePair<User, string>> AlleUser { get; set; }
public MainWindow()
{
InitializeComponent(); // Always the first line in constructor!
this.ListDetailsClick = new ObservableCollection<ListDetails>();
// Initialize ObservableCollection directly
this.ListDetails = new ObservableCollection<ListDetails>()
{
new ListDetails("data 1", new User("1 user", "1")),
new ListDetails("data 2", new User("8 user", "8")),
new ListDetails("data 3", new User("5 user", "5")),
};
this.AlleUser = new ObservableCollection<KeyValuePair<User, string>>()
{
{ new KeyValuePair<User, string>(new User("1 user", "1"), "1") },
{ new KeyValuePair<User, string>(new User("2 user", "2"), "2") },
{ new KeyValuePair<User, string>(new User("4 user", "3"), "3") },
{ new KeyValuePair<User, string>(new User("4 user", "4"), "4") },
{ new KeyValuePair<User, string>(new User("5 user", "5"), "5") },
{ new KeyValuePair<User, string>(new User("6 user", "6"), "6") },
{ new KeyValuePair<User, string>(new User("7 user", "7"), "7") },
{ new KeyValuePair<User, string>(new User("8 user", "8"), "8") },
};
}
private void ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
}
// Clear and copy
private void Button_Click(object sender, RoutedEventArgs e)
{
this.ListDetailsClick.Clear();
this.ListDetails.ToList().ForEach(this.ListDetailsClick.Add);
}
private void Button_Click_1(object sender, RoutedEventArgs e)
{
this.ListDetailsClick.Clear();
}
}